/// <summary>
/// 4,具体装饰器类 加奶
/// </summary>
public class Milk : CondimentDecorator
{
  public Milk(Beverage beverage) : base(beverage) { }

  public override string Description => _beverage.Description + ", Milk";
  public override double Cost() => _beverage.Cost() + 0.10;
}
